Medical device having lithium-ion battery

ABSTRACT

A medical device includes a rechargeable lithium-ion battery for providing power to the medical device. The lithium-ion battery includes a positive electrode including a current collector, a first active material, and a second active material. The lithium-ion battery also includes a negative electrode including a current collector, a third active material, and a quantity of lithium in electrical contact with the current collector of the negative electrode. The second active material exhibits charging and discharging capacity below a corrosion potential of the current collector of the negative electrode and above a decomposition potential of the first active material.

BACKGROUND

The present invention relates generally to the field of lithiumbatteries. Specifically, the present invention relates to lithium-ionbatteries that are relatively tolerant to over discharge conditions andmedical devices which utilize such batteries.

Lithium-ion batteries include a positive current collector (e.g.,aluminum such as an aluminum foil) having an active material providedthereon (e.g., LiCoO₂) and a negative current collector (e.g., coppersuch as a copper foil) having an active material (e.g., a carbonaceousmaterial such as graphite) provided thereon. Together the positivecurrent collector and the active material provided thereon are referredto as a positive electrode, while the negative current collector and theactive material provided thereon are referred to as a negativeelectrode.

FIG. 1 shows a schematic representation of a portion of a lithium-ionbattery 10 such as that described above. The battery 10 includes apositive electrode 20 that includes a positive current collector 22 anda positive active material 24, a negative electrode 30 that includes anegative current collector 32 and a negative active material 34, anelectrolyte material 40, and a separator (e.g., a polymeric microporousseparator, not shown) provided intermediate or between the positiveelectrode 20 and the negative electrode 30. The electrodes 20, 30 may beprovided as relatively flat or planar plates or may be wrapped or woundin a spiral or other configuration (e.g., an oval configuration). Theelectrode may also be provided in a folded configuration.

During charging and discharging of the battery 10, lithium ions movebetween the positive electrode 20 and the negative electrode 30. Forexample, when the battery 10 is discharged, lithium ions flow from thenegative electrode 30 to the to the positive electrode 20. In contrast,when the battery 10 is charged, lithium ions flow from the positiveelectrode 20 to the negative electrode 30.

FIG. 2 is a graph 100 illustrating the theoretical charging anddischarging behavior for a conventional lithium-ion battery. Curve 110represents the electrode potential versus a lithium reference electrodefor a positive electrode that includes an aluminum current collectorhaving a LiCoO₂ active material provided thereon, while curve 120represents the electrode potential versus a lithium reference electrodefor a negative electrode that includes a copper current collector havinga carbonaceous active material provided thereon. The difference betweencurves 110 and 120 is representative of the overall cell voltage.

As shown in FIG. 2, upon initial charging to full capacity, thepotential of the positive electrode, as shown by curve 110, increasesfrom approximately 3.0 volts to a point above the corrosion potential ofcopper used to form the negative electrode (designated by dashed line122). The potential of the negative electrode decreases fromapproximately 3.0 volts to a point below the decomposition potential ofthe LiCoO₂ active material provided on the aluminum current collector(designated by dashed line 112). Upon initial charging, the batteryexperiences an irreversible loss of capacity due to the formation of apassive layer on the negative current collector, which may be referredto as a solid-electrolyte interface (“SEI”). The irreversible loss ofcapacity is shown as a ledge or shelf 124 in curve 120.

One difficulty with conventional lithium-ion batteries is that when sucha battery is discharged to a point near zero volts, it may exhibit aloss of deliverable capacity and corrosion of the negative electrodecurrent collector (copper) and possibly of the battery case, dependingon the material used and the polarity of the case. As shown in FIG. 2,after initial charging of the battery, a subsequent discharge of thebattery in which the voltage of the battery approaches zero volts (i.e.,zero percent capacity) results in a negative electrode potential thatfollows a path designated by dashed line 126. As shown in FIG. 2, thenegative electrode potential levels off or plateaus at the coppercorrosion potential of the negative current collector (approximately 3.5volts for copper and designated by dashed line 122 in FIG. 2).

The point at which the curves 110 and 120 cross is sometimes referred toas the zero voltage crossing potential, and corresponds to a cellvoltage that is equal to zero (i.e., the difference between the twocurves equals zero at this point). Because of the degradation of thecopper current collector which occurs at the copper corrosion potential,the copper material used for the negative current collector corrodesbefore the cell reaches a zero voltage condition, resulting in a batterythat exhibits a dramatic loss of deliverable capacity.

While FIG. 2 shows the theoretical charging and discharging behavior ofa battery that may experience corrosion of the negative currentcollector when the battery approaches a zero voltage configuration, itshould be noted that there may also be cases in which the activematerial on the positive current collector may degrade innear-zero-voltage conditions. In such cases, the theoretical chargingand discharging potential of the positive electrode versus a lithiumreference electrode would decrease to the decomposition potential of thepositive active material (shown as line 112 in FIG. 2), at which pointthe positive active material would decompose, resulting in potentiallydecreased protection against future over-discharge conditions.

Because damage to the lithium-ion battery may occur in the event of alow voltage condition, conventional lithium-ion batteries may includeprotection circuitry and/or may be utilized in devices that includeprotection circuitry which substantially reduces the current drain fromthe battery (e.g., by disconnecting the battery).

The medical device industry produces a wide variety of electronic andmechanical devices for treating patient medical conditions. Dependingupon the medical condition, medical devices can be surgically implantedor connected externally to the patient receiving treatment. Cliniciansuse medical devices alone or in combination with drug therapies andsurgery to treat patient medical conditions. For some medicalconditions, medical devices provide the best, and sometimes the only,therapy to restore an individual to a more healthful condition and afuller life.

It may be desirable to provide a source of battery power for suchmedical devices, including implantable medical devices. In such cases,it may be advantageous to provide a battery that may be recharged. Itmay also be advantageous to provide a battery that may be discharged toa near zero voltage condition without substantial risk that the batterymay be damaged (e.g., without corroding one of the electrodes or thebattery case, decomposing the positive active material, etc.) such thatthe performance of the battery is degraded in subsequent charging anddischarging operations.

It would be advantageous to provide a battery (e.g., a lithium-ionbattery) that may be discharged to near zero volts without producing asubsequent decrease in the amount of deliverable capacity or producing acorroded negative electrode or battery case. It would also beadvantageous to provide a battery that compensates for the irreversibleloss of capacity resulting from initial charging of the battery to allowthe battery to be used in near zero voltage conditions withoutsignificant degradation to battery performance. It would also beadvantageous to provide a medical device (e.g., an implantable medicaldevice) that utilizes a battery that includes any one or more of theseor other advantageous features.

SUMMARY

An exemplary embodiment relates to a medical device includes arechargeable lithium-ion battery for providing power to the medicaldevice. The lithium-ion battery includes a positive electrode includinga current collector, a first active material, and a second activematerial. The lithium-ion battery also includes a negative electrodeincluding a current collector, a third active material, and a quantityof lithium in electrical contact with the current collector of thenegative electrode. The second active material exhibits charging anddischarging capacity below a corrosion potential of the currentcollector of the negative electrode and above a decomposition potentialof the first active material

Another exemplary embodiment relates to a system for providing atherapeutic treatment to a patient. The system includes a lithium-ionbattery configured to provide power to the system and capable of beingcharged and discharged. The lithium-ion battery includes a positiveelectrode comprising a current collector having a primary activematerial and a secondary active material provided on at least one sidethereof. The lithium-ion battery also includes a negative electrodehaving a negative current collector and an active material provided onthe negative current collector. The secondary active material does notinclude lithium and provides charging and discharging capacity for thepositive electrode below a corrosion potential of the negative currentcollector and above a decomposition potential of the primary activematerial.

Another exemplary embodiment relates to a method of treating a medicalcondition of a patient by providing a therapeutic treatment to thepatient. The method includes providing at least a portion of a medicaldevice in contact with the patient and discharging a battery to providepower to the medical device such that the medical device provides thetherapeutic treatment. The battery includes a positive electrodecomprising a positive current collector, a first active material, and asecond active material. The battery also includes a negative electrodecomprising a negative current collector, a third active material, and aquantity of lithium in electrical contact with the negative currentcollector. The first active material, the second active material, andthe third active material are configured for doping and undoping oflithium ions therefrom. The second active material exhibits charging anddischarging capacity below a corrosion potential of the negative currentcollector and above a decomposition potential of the first activematerial.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a conventional lithium-ionbattery.

FIG. 2 is a graph illustrating the theoretical charging and dischargingbehavior for a conventional lithium-ion battery such as that shownschematically in FIG. 1.

FIG. 3 is a schematic cross-sectional view of a portion of a lithium-ionbattery according to an exemplary embodiment.

FIG. 4 is a schematic cross-sectional view of a portion of a lithium-ionbattery according to another exemplary embodiment.

FIG. 5 is a graph illustrating the theoretical charging and dischargingbehavior for a lithium-ion battery such as that shown in FIG. 3.

FIG. 6 is a schematic view of a system in the form of an implantablemedical device implanted within a body or torso of a patient.

FIG. 7 is schematic view of another system in the form of an implantablemedical device.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

With reference to FIG. 3, a schematic cross-sectional view of a portionof a lithium-ion battery 200 is shown according to an exemplaryembodiment. According to an exemplary embodiment, the battery 200 has arating of between approximately 10 and 1000 milliampere hours (mAh).According to another exemplary embodiment, the battery has a rating ofbetween approximately 100 and 400 mAh. According to another exemplaryembodiment, the battery is an approximately 300 mAh battery. Accordingto another exemplary embodiment, the battery is an approximately 75 mAhbattery.

The battery 200 includes at least one positive electrode 210 and atleast one negative electrode 220. The electrodes may be provided as flator planar components of the battery 200, may be wound in a spiral orother configuration, or may be provided in a folded configuration. Forexample, the electrodes may be wrapped around a relatively rectangularmandrel such that they form an oval wound coil for insertion into arelatively prismatic battery case. According to other exemplaryembodiments, the battery may be provided as a button cell battery, athin film solid state battery, or as another lithium-ion batteryconfiguration.

The battery case (not shown) may be made of stainless steel or anothermetal. According to an exemplary embodiment, the battery case may bemade of titanium, aluminum, or alloys thereof. According to anotherexemplary embodiment, the battery case may be made of a plastic materialor a plastic-foil laminate material (e.g., an aluminum foil providedintermediate a polyolefin layer and a polyester layer).

According to an exemplary embodiment, the negative electrode is coupledto a stainless steel case by a member or tab comprising nickel or anickel alloy. An aluminum or aluminum alloy member or tab may be coupledor attached to the positive electrode. The nickel and aluminum tabs mayserve as terminals for the battery according to an exemplary embodiment.

The dimensions of the battery 200 may differ according to a variety ofexemplary embodiments. For example, according to one exemplaryembodiment in which the electrodes are wound such that they may beprovided in a relatively prismatic battery case, the battery hasdimensions of between approximately 30-40 mm by between approximately20-30 mm by between approximately 5-7 mm. According to another exemplaryembodiment, the dimensions of the battery are approximately 20 mm by 20mm by 3 mm. According to another exemplary embodiment, a battery may beprovided in the form of a button cell type battery having a diameter ofapproximately 30 mm and a thickness of approximately 3 mm. It will beappreciated by those of skill in the art that such dimensions andconfigurations as are described herein are illustrative only, and thatbatteries in a wide variety of sizes, shapes, and configurations may beproduced in accordance with the novel concepts described herein.

An electrolyte 230 is provided intermediate or between the positive andnegative electrodes to provide a medium through which lithium ions maytravel. According to an exemplary embodiment, the electrolyte may be aliquid (e.g., a lithium salt dissolved in one or more non-aqueoussolvents). According to another exemplary embodiment, the electrolytemay be a lithium salt dissolved in a polymeric material such aspoly(ethylene oxide) or silicone. According to another exemplaryembodiment, the electrolyte may be an ionic liquid such asN-methyl-N-alkylpyrrolidinium bis(trifluoromethanesulfonyl)imide salts.According to another exemplary embodiment, the electrolyte may be asolid state electrolyte such as a lithium-ion conducting glass such aslithium phosphorous oxynitride (LiPON).

Various other electrolytes may be used according to other exemplaryembodiments. For example, according to an exemplary embodiment, theelectrolyte may be a 1:1 mixture of ethylene carbonate to diethylenecarbonate (EC:DEC) in a 1.0 M salt of LiPF₆. According to anotherexemplary embodiment, the electrolyte may include a polypropylenecarbonate solvent and a lithium bis-oxalatoborate salt (sometimesreferred to as LiBOB). According to other exemplary embodiments, theelectrolyte may comprise one or more of a PVDF copolymer, aPVDF-polyimide material, and organosilicon polymer, a thermalpolymerization gel, a radiation cured acrylate, a particulate withpolymer gel, an inorganic gel polymer electrolyte, an inorganicgel-polymer electrolyte, a PVDF gel, polyethylene oxide (PEO), a glassceramic electrolyte, phosphate glasses, lithium conducting glasses,lithium conducting ceramics, and an inorganic ionic liquid or gel, amongothers.

A separator 250 is provided intermediate or between the positiveelectrode 210 and the negative electrode 220. According to an exemplaryembodiment, the separator 250 is a polymeric material such as apolypropylene/polyethelene copolymer or another polyolefin multilayerlaminate that includes micropores formed therein to allow electrolyteand lithium ions to flow from one side of the separator to the other.The thickness of the separator 250 is between approximately 10micrometers (μm) and 50 μm according to an exemplary embodiment.According to a particular exemplary embodiment, the thickness of theseparator is approximately 25 μm and the average pore size of theseparator is between approximately 0.02 μm and 0.1 μm.

The positive electrode 210 includes a current collector 212 made of aconductive material such as a metal. According to an exemplaryembodiment, the current collector 212 comprises aluminum or an aluminumalloy. According to an exemplary embodiment, the thickness of thecurrent collector 212 is between approximately 5 μm and 75 μm. Accordingto a particular exemplary embodiment, the thickness of the currentcollector 212 is approximately 20 μm. It should also be noted that whilethe positive current collector 212 has been illustrated and described asbeing a thin foil material, the positive current collector may have anyof a variety of other configurations according to various exemplaryembodiments. For example, the positive current collector may be a gridsuch as a mesh grid, an expanded metal grid, a photochemically etchedgrid, or the like.

The current collector 212 has a layer of active material 214 providedthereon (e.g., coated on the current collector). While FIG. 3 shows thatthe layer of active material 214 is provided on only one side of thecurrent collector 212, it should be understood that a layer of activematerial similar or identical to that shown as layer 214 may be providedor coated on both sides of the current collector 212.

As shown in FIG. 3, layer 214 includes a primary active material 216 anda secondary or auxiliary active material 218. While the primary activematerial 216 and the secondary active material 218 are shown as beingprovided as separate individual layers according to an exemplaryembodiment, it will be appreciated that the primary active material 216and the secondary active material 218 may be provided as a single activematerial layer in which the primary and secondary active materials areintermixed (see, e.g., the exemplary embodiment shown in FIG. 4, inwhich layer 214 includes both the primary active material 216 and thesecondary active material 218). A binder material may also be utilizedin conjunction with the layer of active material 214 to bond or hold thevarious electrode components together. For example, according to anexemplary embodiment, the layer of active material may include aconductive additive such as carbon black and a binder such aspolyvinylidine fluoride (PVDF) or an elastomeric polymer.

According to an exemplary embodiment, the primary active material 216 isa material or compound that includes lithium. The lithium included inthe primary active material 216 may be doped and undoped duringdischarging and charging of the battery, respectively. According to anexemplary embodiment, the primary active material 216 is lithium cobaltoxide (LiCoO₂). According to another exemplary embodiment, the positiveactive material is of the form LiCo_(x)Ni_((1−x))O₂, where x is betweenapproximately 0.05 and 0.8. According to another exemplary embodiment,the primary active material is of the form LiAl_(x)Co_(y)Ni_((1−x−y))O₂,where x is between approximately 0.05 and 0.3 and y is betweenapproximately 0.1 and 0.3. According to other exemplary embodiments, theprimary active material may include LiMn₂O₄.

According to various other exemplary embodiments, the primary activematerial may include a material such as a material of the formLi_(1−x)MO₂ where M is a metal (e.g., LiCoO₂, LiNiO₂, and LiMnO₂), amaterial of the form Li_(1−w)(M′_(x)M″_(y))O₂ where M′ and M″ aredifferent metals (e.g., Li(Ni_(x)Mn_(y))O₂, Li(Ni_(1/2)Mn_(1/2))O₂,Li(Cr_(x)Mn_(1−x))O₂, Li(Al_(x)Mn_(1−x))O₂, Li(Co_(x)M_(1−x))O₂ where Mis a metal, Li(Co_(x)Ni_(1−x))O₂, and Li(Co_(x)Fe_(1−x))O₂)), a materialof the form Li_(1−w)(Mn_(x)Ni_(y)Co_(z))O₂ (e.g.,LiCo_(x)Mn_(y)Ni(_(1−x−y))O₂, Li(Mn_(1/3)Ni_(1/3)CO_(1/3))O₂,Li(Mn_(1/3)Ni_(1/3)Co_(1/3−x)Mg_(x))O₂, Li(Mn_(0.4)Ni_(0.4)Co_(0.2))O₂,and Li(Mn_(0.1)Ni_(0.1)Co_(0.8))O₂), a material of the formLi_(1−w)(Mn_(x)Ni_(x)Co_(1−2x))O₂, a material of the formLi_(1−w)(Mn_(x)Ni_(y)Co_(z)Al_(w))O₂ a material of the formLi_(1−w)(Ni_(x)Co_(y)Al_(z))O₂ (e.g., Li(Ni_(0.8)Co_(0.15)Al_(0.05))O₂),a material of the form Li_(1−w)(Ni_(x)Co_(y)M_(z))O₂ where M is a metal,a material of the form Li_(1−w)(Ni_(x)Mn_(y)M_(z))O₂ where M is a metal,a material of the form Li(Ni_(x−y)Mn_(y)Cr_(2−x))O₄ LiMn₂O₄, a materialof the form LiM′M″₂O₄ where M′ and M″ are different metals (e.g.,LiMn_(2−y−z) Ni_(y), Li_(z)O₄, LiMn_(1.5) Ni_(0.5)O₄, LiNiCuO₄,LiMn_(1−x) Al_(x)O₄, LiNi_(0.5)Ti_(0.5)O₄, andLi_(1.05)Al_(0.1)Mn_(1.85)O_(4−z)F_(z)), Li₂MnO₃, a material of the formLi_(x)V_(y)O_(z) (e.g., LiV₃O₈, LiV₂O₅, and LiV₆O₁₃), a material of theform LiMPO₄ where M is a metal or LiM_(x)′M″_(1−x)PO₄ where M′ and M″are different metals (e.g., LiFePO₄, LiFe_(x)M_(1−x)PO₄ where M is ametal, LiVOPO₄, and Li₃V₂(PO₄)₃, LiMPO_(4x) where M is a metal such asiron or vanadium and X is a halogen such as fluorine, and combinationsthereof.

The secondary active material 218 is a material that is selected to haverelatively significant cyclable charge and discharge capacity (i.e.,cyclable capacity) below the corrosion potential of the material usedfor a negative current collector 222 provided as part of the negativeelectrode 220 (and/or any other material to which the negative currentcollector is electrically attached or in electrical communication with,for example, a case or housing for the battery) and above thedecomposition potential of the primary active material 216. For example,according to an exemplary embodiment in which the negative currentcollector 222 comprises copper, for which the corrosion potential isapproximately 3.5 volts, the secondary active material 218 includessignificant charge and discharge capacity below 3.5 volts.

The secondary active material 218 may or may not contain lithium.According to an exemplary embodiment in which the secondary activematerial does not include lithium, the secondary active material isV₆O₁₃. According to another exemplary embodiment in which the secondaryactive material includes lithium, the secondary active material isLiMn₂O₄. According to various other exemplary embodiments, the secondaryactive material may be selected from the following materials andcombinations thereof: V₂O₅, V₆O₁₃, LiMn₂O₄ (spinel), LiM_(x)Mn_((2−x))O₄(spinel) where M is metal (including Li) and where x is betweenapproximately 0.05 and 0.4, Li₄Ti₅O₁₂, Li_(x)VO₂ (where x is betweenapproximately 0 and 1), V₃O₈, MoO₃, TiS₂, WO₂, MoO₂, and RuO₂.

According to an exemplary embodiment, electrochemically active orcyclable lithium may be added as finely divided or powdered lithium.Such powdered lithium may include a passive coating (e.g., a thin layeror film of lithium carbonate) provided thereon to reduce the reactivityof the powdered lithium with air and moisture. Such material may bemixed with the secondary active material prior to application of thesecondary active material to fabrication of the cells or may be added asanother separate active material layer.

The lithium added to the secondary active material 218 of the positiveelectrode 210 has significant charge/discharge capacity that lies belowthe corrosion potential of the negative current collector and/or anybattery components to which it is electrically connected (e.g., thecase) and above the decomposition potential of the positive electrodeactive material. The lithium becomes significantly doped at a potentialbelow the corrosion potential for the negative current collector 222. Inso doing, this material lowers the final potential of the positiveelectrode in the discharge state, so that the zero voltage crossingpotential remains below the corrosion potential of the negative currentcollector and the battery case. The secondary active material may becapable of releasing the lithium when the battery is charged.

It should be noted that while a variety of materials have been describedabove as being useful for secondary active material 218, a variety ofadditional materials may be utilized in addition to or in place of suchmaterials. For example, the secondary active material may comprise anoxide material such as one or more of Li_(x)MoO₃ (0<x≦2), Li_(x)MoO₂(0<x≦1), Li_(x)Mo₂O₄ (0<x≦2), Li_(x)MnO₂ (0<x≦1), Li_(x)Mn₂O₄ (0<x≦2),Li_(x)V₂O₅ (0<x≦2.5), Li_(x)V₃O₈ (0<x≦3.5), Li_(x)V₆O₁₃ (0<x≦6 forLi_(x)VO_(2.19) and 0<x≦3.6 for Li_(x)VO_(2.17)), Li_(x)VO₂ (0<x≦1),Li_(x)WO₃ (0<x≦1), Li_(x)WO₂ (0<x≦1), Li_(x)TiO₂ (anatase) (0<x≦1),Li_(x)Ti₂O₄ (0<x≦2), Li_(x)RuO₂ (0<x≦1), Li_(x)Fe₂O₃ (0<x≦2),Li_(x)Fe₃O₄ (0<x≦2), Li_(x)Cr₂O (0<x≦3), Li_(x)Cr (0<x≦3.8), andLi_(x)Ni_(y)Co_(1−y)O₂ (0<x≦1, 0.90<y≦1.00), where x is selected suchthat these materials have little or no lithium that becomes undopedbelow the corrosion potential of the negative current collector duringthe first charge of the battery.

According to another exemplary embodiment, the secondary active materialmay comprise a sulfide material such as one or more of Li_(x)V₂S₅(0<x≦4.8), Li_(x)TaS₂ (0<x≦1), Li_(x)FeS (0<x≦1), Li_(x)FeS₂ (0<x≦1),Li_(x)NbS₃ (0<x≦2.4), Li_(x)MoS₃ (0<x≦3), Li_(x)MoS₂ (0<x≦1), Li_(x)TiS₂(0<x≦1), Li_(x)ZrS₂ (0<x≦1), Li_(x)Fe_(0.25) V_(0.75)S₂ (0<x≦1),Li_(x)Cr_(0.75)V_(0.25)S₂ (0<x≦0.65), and Li_(x)Cr_(0.5)V_(0.5)S₂(0<x≦1), where x is selected such that these materials have little or nolithium that becomes undoped below corrosion potential of the negativecurrent collector during the first charge of the battery.

According to another exemplary embodiment, the secondary active materialmay comprise a selenide material such as one or more of Li_(x)NbSe₃(0<x≦3), Li_(x)VSe₂ (0<x≦1). Various other materials may also be used,for example, Li_(x)NiPS₃ (0<x≦1.5) and Li_(x)FePS₃ (0<x≦1.5), where x isselected such that these materials have little or no lithium thatbecomes undoped below corrosion potential of the negative currentcollector during the first charge of the battery.

According to an exemplary embodiment, the thickness of the layer ofactive material 214 is between approximately 0.1 μm and 3 mm. Accordingto another exemplary embodiment, the thickness of the layer of activematerial 214 is between approximately 25 μm and 300 μm. According to aparticular exemplary embodiment, the thickness of the layer of activematerial 214 is approximately 75 μm. In embodiments in which the primaryactive material 216 and the secondary active material 218 are providedas separate layers of active material, the thickness of the primaryactive material 216 is between approximately 25 μm and 300 μm (andapproximately 75 μm according to a particular exemplary embodiment),while the thickness of the secondary active material 218 is betweenapproximately 5 μm and 60 μm (and approximately 10 μm according to aparticular exemplary embodiment). The amount of the secondary activematerial 218 to be added is determined by the electrochemicalequivalents (i.e., capacity) of lithium that can be cycled from thatmaterial. According to an exemplary embodiment, the amount is as smallas practical, because this minimizes the amount to which the battery'saverage operating voltage (and therefore energy density) is reduced.According to another exemplary embodiment, the amount is at a minimumequal to the difference between the irreversible capacity of thenegative electrode active material and that of the positive activematerial.

The negative current collector 222 included as part of the negativeelectrode 220 is made of a conductive material such as a metal.According to an exemplary embodiment, the current collector 222 iscopper or a copper alloy. According to another exemplary embodiment, thecurrent collector 222 is titanium or a titanium alloy. According toanother exemplary embodiment, the current collector 222 is nickel or anickel alloy. According to another exemplary embodiment in which the,negative active material 224 is not carbon, the current collector 222 isaluminum or an aluminum alloy. It should also be noted that while thenegative current collector 222 has been illustrated and described asbeing a thin foil material, the positive current collector may have anyof a variety of other configurations according to various exemplaryembodiments. For example, the positive current collector may be a gridsuch as a mesh grid, an expanded metal grid, a photochemically etchedgrid, or the like.

According to an exemplary embodiment, the thickness of the currentcollector 222 is between approximately 100 nm and 100 μm. According toanother exemplary embodiment, the thickness of the current collector 222is between approximately 5 μm and 25 μm. According to a particularexemplary embodiment, the thickness of the current collector 222 isapproximately 10 μm.

The negative current collector 222 has a negative active material 224provided thereon. While FIG. 3 shows that the active material 224 isprovided on only one side of the current collector 222, it should beunderstood that a layer of active material similar or identical to thatshown may be provided or coated on both sides of the current collector222.

According to exemplary embodiment, the negative active material 224 is acarbonaceous material (e.g., carbon such as graphite). According toexemplary embodiment, the negative active material 224 is a lithiumtitanate material such as Li₄Ti₅O₁₂. Other lithium titanate materialswhich may be suitable for use as the negative active material mayinclude one or more of the following lithium titanate spinel materials:H_(x)Li_(y−x)TiO_(x)O₄, H_(x)Li_(y−x)TiO_(x)O₄, Li₄M_(x)Ti_(5−x)O₁₂,Li_(x)Ti_(y)O₄, Li_(x)Ti_(y)O₄, Li₄[Ti_(1.67)Li_(0.33−y)M_(y)]O₄,Li₂TiO₃, Li₄Ti_(4.75)V_(0.25)O₁₂, Li₄Ti_(4.75)Fe_(0.25)O_(11.88), andLi₄Ti_(4.5)Mn_(0.5)O₁₂, and LiM′M″XO₄ (where M′ is a metal such asnickel, cobalt, iron, manganese, vanadium, copper, chromium, molybdenum,niobium, or combinations thereof, M″ is an optional three valentnon-transition metal, and X is zirconium, titanium, or a combination ofthese two). Note that such lithium titanate spinel materials may be usedin any state of lithiation (e.g., Li_(4+x)Ti₅O₁₂, where 0≦x≦3).

One advantage of using a lithium titanate material instead of acarbonaceous material is that it is believed that the use of a lithiumtitanate material allows for charging and discharging of the battery athigher rates than is capable using carbonaceous materials. Lithiumtitanate materials are also believed to offer superior cycle lifebecause they are so called “zero-strain” materials. Zero strainmaterials have crystal lattices which do not experience shrinkage orcontraction with lithium doping/de-doping, making them free fromstrain-related degradation mechanisms. According to other exemplaryembodiments, the negative active material 224 may be carbon, Li_(x)Al,Li_(x)Sn, Li_(x)Si, Li_(x)SnO, metal nanoparticle composites (e.g.,including Li_(x)Al, Li_(x)Sn, Li_(x)Si, or Li_(x)SnO), or carbon-coatedlithium titanate.

Another advantageous feature of using a lithium titanate material isthat it is believed that when used in a negative electrode of alithium-ion battery, such materials will cycle lithium at a potentialplateau of about 1.5 V versus a lithium reference electrode. This issubstantially higher than graphitic carbon, which is traditionally usedin lithium ion batteries, and cycles lithium down to about 0.1 V in thefully charged state. As a result, the battery using lithium titanate isbelieved to be less likely to result in plating of lithium (which occursat 0 V versus a lithium reference) while being charged. Lithium platingis a well-known phenomenon that can lead to loss in performance oflithium ion batteries. Being free from the risk of lithium plating,cells with lithium titanate negative electrodes may also be charged atrates that exceed those with carbon negative electrodes. For example, acommon upper limit for the rate of charge in lithium ion batteries isabout 1 C (meaning that the battery can be fully charged from thedischarged state in one hour). Conversely, it has been reported inliterature that lithium titanate may be charged at rates up to 10 C(i.e., attaining full charge in 1/10 hour, or six minutes). Being ableto recharge a battery more quickly substantially increases thefunctionality of devices that employ such a battery. A further advantageof the higher potential of the lithium titanate material is that itavoids decomposition of organic solvents (such as propylene carbonate)commonly used in lithium ion batteries. In so doing, it may reducenegative consequences such as formation of gas, cell swelling, reductionof reversible battery capacity, and buildup of resistive films whichreduce battery power.

A binder material may also be utilized in conjunction with the layer ofactive material 224. For example, according to an exemplary embodiment,the layer of active material may include a conductive additive such ascarbon black and a binder such as polyvinylidine fluoride (PVDF) or anelastomeric polymer.

According to various exemplary embodiments, the thickness of the activematerial 224 is between approximately 0.1 μm and 3 mm. According toother exemplary embodiments, the thickness of the active material 224may be between approximately 25 μm and 300 μm. According to anotherexemplary embodiment, the thickness of the active material 224 may bebetween approximately 20 μm and 90 μm, and according to a particularexemplary embodiment, may be approximately 75 μm.

As shown in FIG. 3, a mass or quantity of electrochemically activelithium (shown as a piece of lithium in the form of a lithium patch ormember 240) is shown as being coupled or attached to (e.g., inelectrical contact with) the negative current collector 222. Such aconfiguration corresponds to a situation in which the secondary activematerial 218 is provided without including electrochemically activelithium (e.g., the secondary active material 218 does not includelithium as it is coated on the positive current collector). One suchexemplary embodiment involves the use of V₆O₁₃ for the secondary activematerial. It should also be noted that electrochemically cyclablelithium may be added by adding lithium-containing compounds such as alithium intermetallic compound such as a lithium-aluminum compound, alithium-tin compound, a lithium-silicon compound, or any other similarcompound that irreversibly donates lithium at a potential below that ofthe corrosion potential of the negative current collector (and anymaterial to which it is electrically connected).

The electrochemically active lithium may be provided in other locationsin the negative electrode 220 and/or may have a different size or shapethan that shown schematically in FIG. 3. For example, theelectrochemically active lithium may be provided as a disc or as arectangular piece of material coupled to the negative current collector.While the electrochemically active lithium is shown as being provided ona single side of the current collector 222 in FIG. 3 (e.g., as a lithiumpatch), separate lithium patches may be provided on opposite sides ofthe current collector 222. Further, multiple lithium patches may beprovided on one or more of the sides of the current collector 222. Inanother example, the lithium may be provided elsewhere within thebattery and connected (e.g., by a wire) to the current collector 222.

According to another exemplary embodiment, the electrochemically activeor cyclable lithium may be added as finely divided or powdered lithium.Such powdered lithium may include a passive coating (e.g., a thin layeror film of lithium carbonate) provided thereon to reduce the reactivityof the powdered lithium with air and moisture. Such material may bemixed with the negative electrode active material prior to applicationof the negative electrode active material to fabrication of the cells ormay be added as another separate active material layer. According to anexemplary embodiment, the finely divided or powdered lithium particleshave a diameter of between approximately 1 μm and 100 μm, and accordingto a particular embodiment, between approximately 5 μm and 30 μm.

One advantage of providing electrochemically active lithium at thenegative electrode (e.g., in the form of one or more lithium patches) isthat the secondary active material 218 may be partially or completelylithiated by the lithium to compensate for the irreversible loss ofcapacity which occurs upon the first charging of the battery 200. Forexample, when the battery cell is filled with electrolyte, lithium fromthe lithium patch 240 is oxidized and inserted into the negative activematerial (i.e., the lithium in the electrochemically active lithium iseffectively “shorted” to the negative active material).

The electrochemically active lithium may also provide a number ofadditional advantages. For example, it may act to maintain the potentialof the negative current collector below its corrosion potential prior toinitial charging (“formation”) of the battery. The electrochemicallyactive lithium may also aid in the formation of the solid-electrolyteinterface (“SEI”) at the negative electrode. Further, theelectrochemically active lithium may provide the “formation” of theactive material on the negative electrode without a correspondingreduction in battery capacity as would occur when the source of lithiumfor formation is the active material from the positive electrode.

The amount of electrochemically active lithium is selected such that theamount of electrochemical equivalents provided by the electrochemicallyactive lithium at minimum corresponds to the irreversible capacity ofthe negative electrode active material and at maximum corresponds to thesum of the irreversible capacity of the negative electrode activematerial and the capacity of the secondary active material 218. In thismanner, the electrochemically active lithium at least compensates forthe irreversible loss of capacity which occurs on initial charging ofthe battery 200 and most preferably corresponds to the sum of theirreversible capacity of the negative electrode active material and thecapacity of the secondary active material 218.

According to an exemplary embodiment in which a lithium patch 240 isutilized, the size the lithium patch 240 is between approximately 1.4cm×1.4 cm×0.11 cm, which corresponds to approximately 0.013 grams (e.g.,approximately 50 mAh). The specific size of the lithium patch may varyaccording to other exemplary embodiments (e.g., approximately 5-25percent of the capacity of either the negative or positive electrode).

FIG. 5 is a graph 300 illustrating the theoretical charging anddischarging behavior for a lithium-ion battery constructed in accordancewith an exemplary embodiment such as that shown and described withregard to FIG. 3. Curve 310 represents the electrode potential versus alithium reference electrode for a positive electrode (e.g., positiveelectrode 210) that includes an aluminum current collector having aLiCoO₂ primary active material and a secondary active material providedthereon.

The secondary active material is selected to provide significantcharging/discharging capacity below the corrosion potential (shown asdashed line 322) of the negative current collector and above thedecomposition potential (shown as dashed line 312) of the LiCoO₂ primaryactive material. According to an exemplary embodiment, the secondaryactive material is V₆O₁₃ or LiMn₂O₄. According to various otherexemplary embodiments, the secondary active material may be selectedfrom the following materials and combinations thereof: V₂O₅, LiMn₂O₄,V₆O₁₃, LiM_(x)Mn_((2−x))O₄ (spinel) where M is metal (including Li),Li₄Ti₅O₁₂, Li_(x)VO₂, V₃O₈, MoO₃, TiS₂, WO₂, MoO₂, and RuO₂.

Curve 320 represents the electrode potential versus a lithium referenceelectrode for a negative electrode that includes a copper currentcollector having a carbonaceous active material (i.e., carbon) and alithium patch provided thereon. The difference between curves 310 and320 is representative of the overall cell voltage of the battery.

It should be noted that the theoretical charging and discharge behaviorfor the negative electrode is believed to be qualitatively similar tothat shown in FIG. 5 for a copper current collector having a Li₄Ti₅O₁₂active material provided thereon (as opposed to a carbon activematerial), with the relatively flat portion of the curve 320 beingshifted upward to a level of approximately 1.57 volts (in contrast tothe approximately 0.1 volts for the carbon active material).

Upon initial charging, the battery experiences an irreversible loss ofcapacity due to the formation of a passive layer on the negativeelectrode, which may be referred to as a solid-electrolyte interface(“SEI”). The irreversible loss of capacity is shown as a ledge or shelf324 in curve 320. The lithium patch is provided so as to compensate forthe irreversible loss of capacity and to provide lithium to the secondactive material in the event of discharge to a voltage approaching zero.For example, as shown in FIG. 5, the relative capacity provided by thelithium patch is shown by arrow 328.

As shown in FIG. 5, the initial state of the cell, after it is filledwith electrolyte and allowed to equilibrate, is indicated by dashed lineXXX. The potential of the positive electrode, as shown by curve 310, isapproximately 3 volts (shown as point 311). The potential of thenegative electrode, as shown by curve 320, is approximately 0.1 volts(shown as point YYY). When the cell is charged, the potentials of thepositive and negative electrodes progress to the right along curves 310and 320, respectively. When the cell is discharged, the potentials ofthe positive and negative electrode potentials progress toward the left.

The charging/discharging behavior of the primary and secondary activematerials (e.g., primary active material 216 and secondary activematerial 218) provided on the positive current collector are shown inFIG. 5 as two portions 314, 316 of curve 310. Portion 314 of curve 310represents the charging/discharging behavior of the positive electrodedue to the doping and undoping of the primary active material (i.e.,LiCoO₂), while portion 316 of curve 310 represents thecharging/discharging behavior of the positive electrode due to thedoping and undoping of the secondary active material (i.e., V₆O₁₃,LiMn₂O₄, etc.).

Upon discharging the battery to a point approaching zero volts, thenegative electrode potential follows a path designated by line 326.However, because the secondary active material is chosen to havesignificant charging/discharging capacity below the corrosion potentialof the negative current collector and above the decomposition potentialof the LiCoO₂ primary active material, the zero voltage crossingpotential (shown as point 330) is below the corrosion potential of thenegative current collector and above the decomposition potential of theLiCoO₂ primary active material, thus avoiding corrosion of the negativecurrent collector (and potentially of the battery case) and anyassociated loss of battery charging capacity.

It is intended that a lithium-ion battery such as that described hereinmay be fully discharged while the materials for both electrodes,including their corresponding current collectors, are stable (e.g.,corrosion of the current collectors and/or the decomposition of activematerial may be avoided, etc.). One potential advantageous feature ofsuch an arrangement is that the occurrence of reduced devicefunctionality (i.e., the need to recharge more frequently) and corrosionof the current collectors and battery case (with the incumbentpossibility of leaking potentially corrosive and toxic battery contents)may be reduced or avoided. Another advantageous feature of such anarrangement is that the battery may be repeatedly cycled (i.e., chargedand discharged) to near-zero-voltage conditions without significantdecline in battery performance.

Various advantageous features may be obtained by utilizing batteriessuch as those shown and described herein. For example, use of suchbatteries may eliminate the need to utilize circuitry to disconnectbatteries approaching near-zero voltage conditions. By not utilizingcircuitry for this function, volume and cost reductions may be obtained.

According to an exemplary embodiment, lithium-ion batteries such asthose described above may be used in conjunction with medical devicessuch as medical devices that may be implanted in the human body(referred to as “implantable medical devices” or “IMD's”).

FIG. 6 illustrates a schematic view of a system 400 (e.g., animplantable medical device) implanted within a body or torso 432 of apatient 430. The system 400 includes a device 410 in the form of animplantable medical device that for purposes of illustration is shown asa defibrillator configured to provide a therapeutic high voltage (e.g.,700 volt) treatment for the patient 430.

The device 410 includes a container or housing 414 that is hermeticallysealed and biologically inert according to an exemplary embodiment. Thecontainer may be made of a conductive material. One or more leads 416electrically connect the device 410 and to the patient's heart 420 via avein 422. Electrodes 417 are provided to sense cardiac activity and/orprovide an electrical potential to the heart 420. At least a portion ofthe leads 416 (e.g., an end portion of the leads shown as exposedelectrodes 417) may be provided adjacent or in contact with one or moreof a ventricle and an atrium of the heart 420.

The device 410 includes a battery 440 provided therein to provide powerfor the device 410. According to another exemplary embodiment, thebattery 440 may be provided external to the device or external to thepatient 430 (e.g., to allow for removal and replacement and/or chargingof the battery). The size and capacity of the battery 440 may be chosenbased on a number of factors, including the amount of charge requiredfor a given patient's physical or medical characteristics, the size orconfiguration of the device, and any of a variety of other factors.According to an exemplary embodiment, the battery is a 5 mAh battery.According to another exemplary embodiment, the battery is a 300 mAhbattery. According to various other exemplary embodiments, the batterymay have a capacity of between approximately 10 and 1000 mAh.

According to other exemplary embodiments, more than one battery may beprovided to power the device 410. In such exemplary embodiments, thebatteries may have the same capacity or one or more of the batteries mayhave a higher or lower capacity than the other battery or batteries. Forexample, according to an exemplary embodiment, one of the batteries mayhave a capacity of approximately 500 mAh while another of the batteriesmay have a capacity of approximately 75 mAh.

According to another exemplary embodiment shown in FIG. 7, animplantable neurological stimulation device 500 (an implantable neurostimulator or INS) may include a battery 502 such as those describedabove with respect to the various exemplary embodiments. Examples ofsome neuro stimulation products and related components are shown anddescribed in a brochure titled “Implantable Neurostimulation Systems”available from Medtronic, Inc.

An INS generates one or more electrical stimulation signals that areused to influence the human nervous system or organs. Electricalcontacts carried on the distal end of a lead are placed at the desiredstimulation site such as the spine or brain and the proximal end of thelead is connected to the INS. The INS is then surgically implanted intoan individual such as into a subcutaneous pocket in the abdomen,pectoral region, or upper buttocks area. A clinician programs the INSwith a therapy using a programmer. The therapy configures parameters ofthe stimulation signal for the specific patient's therapy. An INS can beused to treat conditions such as pain, incontinence, movement disorderssuch as epilepsy and Parkinson's disease, and sleep apnea. Additionaltherapies appear promising to treat a variety of physiological,psychological, and emotional conditions. Before an INS is implanted todeliver a therapy, an external screener that replicates some or all ofthe INS functions is typically connected to the patient to evaluate theefficacy of the proposed therapy.

The INS 500 includes a lead extension 522 and a stimulation lead 524.The stimulation lead 524 is one or more insulated electrical conductorswith a connector 532 on the proximal end and electrical contacts (notshown) on the distal end. Some stimulation leads are designed to beinserted into a patient percutaneously, such as the Model 3487APisces-Quad® lead available from Medtronic, Inc. of Minneapolis Minn.,and stimulation some leads are designed to be surgically implanted, suchas the Model 3998 Specify® lead also available from Medtronic.

Although the lead connector 532 can be connected directly to the INS 500(e.g., at a point 536), typically the lead connector 532 is connected toa lead extension 522. The lead extension 522, such as a Model 7495available from Medtronic, is then connected to the INS 500.

Implantation of an INS 520 typically begins with implantation of atleast one stimulation lead 524, usually while the patient is under alocal anesthetic. The stimulation lead 524 can either be percutaneouslyor surgically implanted. Once the stimulation lead 524 has beenimplanted and positioned, the stimulation lead's 524 distal end istypically anchored into position to minimize movement of the stimulationlead 524 after implantation. The stimulation lead's 524 proximal end canbe configured to connect to a lead extension 522.

The INS 500 is programmed with a therapy and the therapy is oftenmodified to optimize the therapy for the patient (i.e., the INS may beprogrammed with a plurality of programs or therapies such that anappropriate therapy may be administered in a given situation). In theevent that the battery 502 requires recharging, an external lead (notshown) may be used to electrically couple the battery to a chargingdevice or apparatus.

A physician programmer and a patient programmer (not shown) may also beprovided to allow a physician or a patient to control the administrationof various therapies. A physician programmer, also known as a consoleprogrammer, uses telemetry to communicate with the implanted INS 500, soa clinician can program and manage a patient's therapy stored in the INS500, troubleshoot the patient's INS 500 system, and/or collect data. Anexample of a physician programmer is a Model 7432 Console Programmeravailable from Medtronic. A patient programmer also uses telemetry tocommunicate with the INS 500, so the patient can manage some aspects ofher therapy as defined by the clinician. An example of a patientprogrammer is a Model 7434 Itrel® 3 EZ Patient Programmer available fromMedtronic.

While the medical devices described herein (e.g., systems 400 and 500)are shown and described as a defibrillator and a neurologicalstimulation device, it should be appreciated that other types ofimplantable medical devices may be utilized according to other exemplaryembodiments, such as pacemakers, cardioverters, cardiac contractilitymodulators, drug administering devices, diagnostic recorders, cochlearimplants, and the like for alleviating the adverse effects of varioushealth ailments. According to still other embodiments, non-implantablemedical devices or other types of devices may utilize batteries as areshown and described in this disclosure.

It is also contemplated that the medical devices described herein may becharged or recharged when the medical device is implanted within apatient. That is, according to an exemplary embodiment, there is no needto disconnect or remove the medical device from the patient in order tocharge or recharge the medical device. For example, transcutaneousenergy transfer (TET) may be used, in which magnetic induction is usedto deliver energy from outside the body to the implanted battery,without the need to make direct physical contact to the implantedbattery, and without the need for any portion of the implant to protrudefrom the patient's skin. According to another exemplary embodiment, aconnector may be provided external to the patient's body that may beelectrically coupled to a charging device in order to charge or rechargethe battery. According to other exemplary embodiments, medical devicesmay be provided that may require removal or detachment from the patientin order to charge or recharge the battery.

It is also important to note that the construction and arrangement ofthe lithium-ion battery as shown and described with respect to thevarious exemplary embodiments is illustrative only. Although only a fewembodiments of the present inventions have been described in detail inthis disclosure, those skilled in the art who review this disclosurewill readily appreciate that many modifications are possible (e.g.,variations in sizes, dimensions, structures,.shapes and proportions ofthe various elements, values of parameters, mounting arrangements, useof materials, colors, orientations, etc.) without materially departingfrom the novel teachings and advantages of the subject matter recited inthe claims. Accordingly, all such modifications are intended to beincluded within the scope of the present invention as defined in theappended claims. Other substitutions, modifications, changes andomissions may be made in the design, operating conditions andarrangement of the preferred and other exemplary embodiments withoutdeparting from the scope of the present invention as expressed in theappended claims.

1. A medical device comprising: a rechargeable lithium-ion battery forproviding power to the medical device, the lithium-ion batterycomprising: a positive electrode comprising a current collector, a firstactive material, and a second active material; and a negative electrodecomprising a current collector, a third active material, and a quantityof lithium in electrical contact with the current collector of thenegative electrode; wherein the quantity of lithium provideselectrochemically cyclable lithium for the second active material of thepositive electrode to allow the second active material to exhibitcharging and discharging capacity below a corrosion potential of thecurrent collector of the negative electrode and above a decompositionpotential of the first active material; whereby the rechargeablelithium-ion battery may be discharged completely without a substantialreduction in battery capacity during subsequent charge cycling of thebattery.
 2. The medical device of claim 1, wherein at least a portion ofthe medical device is configured for implantation into a body of apatient.
 3. The medical device of claim 2, wherein the lithium-ionbattery may be charged without removing the medical device from the bodyof the patient.
 4. The medical device of claim 1, wherein the medicaldevice comprises a neurological stimulation device.
 5. The medicaldevice of claim 4, wherein the neurological stimulation device isconfigured to provide a therapeutic treatment to a patient byelectrically stimulating a portion of the patient's brain.
 6. Themedical device of claim 5, wherein the neurological stimulation deviceis programmed to selectively provide a plurality of therapeutictreatments to a patient.
 7. The medical device of claim 1, wherein themedical device is selected from the group consisting of a cardiacdefibrillator, a cardiac pacemaker, a cardiac contractility modulator, acardioverter, a drug administration device, a cochlear implant, ahearing aid, a sensor, a telemetry device, and a diagnostic recorder. 8.The medical device of claim 7, wherein the device is an implantablecardiac defibrillator for providing a therapeutic high voltage treatmentto a patient.
 9. The medical device of claim 8, further comprising atleast one lead extending from the defibrillator and configured forcontacting a portion of a patient's heart.
 10. The medical device ofclaim 1, wherein the positive electrode and the negative electrode havea zero voltage crossing potential below a corrosion potential of thecurrent collector of the negative electrode and above a decompositionpotential of the first active material.
 11. The medical device of claim1, wherein the quantity of lithium is provided in the form of a lithiumpatch coupled to the current collector of the negative electrode and isconfigured to provide a lithium capacity for the negative electrodesufficient to at least compensate for irreversible loss of capacity ofthe negative electrode.
 12. The medical device of claim 1, wherein thequantity of lithium is provided as powdered lithium.
 13. The medicaldevice of claim 1, wherein the current collector of the negativeelectrode comprises copper.
 14. The medical device of claim 1, whereinthe current collector of the negative electrode comprises at least onetitanium, aluminum, and nickel.
 15. The medical device of claim 1,wherein the first active material comprises at least one of LiCoO₂,LiCo_(1/3)Mn_(1/3)Ni_(1/3)O₂, LiNi_(x)Co_(y)Al_(z)O₂, andLiCo_(x)Ni_((1−x))O₂.
 16. The medical device of claim 1, wherein thesecond active material does not include lithium.
 17. The medical deviceof claim 1, wherein the second active material comprises V₆O₁₃.
 18. Themedical device of claim 1, wherein the second active material comprisesLiMn₂O₄.
 19. The medical device of claim 1, wherein the second activematerial comprises a material selected from the group consisting ofV₂O₅, Li₄Ti₅O₁₂, Li_(x)VO₂, V₃O₈, MoO₃, TiS₂, WO₂, MoO₂, RuO₂, andcombinations thereof.
 20. The medical device of claim 1, wherein thethird active material is a carbonaceous material.
 21. The medical deviceof claim 1, wherein the third active material is a lithium titanatematerial.
 22. The medical device of claim 1, wherein the battery has acapacity between approximately 10 mAh and 1000 mAh.
 23. A system forproviding a therapeutic treatment to a patient comprising: a lithium-ionbattery configured to provide power to the system and capable of beingcharged and discharged, the lithium-ion battery comprising: a positiveelectrode comprising a current collector having a primary activematerial and a secondary active material provided on at least one sidethereof; a negative electrode having a negative current collector and anactive material provided on the negative current collector; wherein thesecondary active material does not include lithium and provides chargingand discharging capacity for the positive electrode below a corrosionpotential of the negative current collector and above a decompositionpotential of the primary active material.
 24. The system of claim 23,wherein at least a portion of the system is configured for implantationinto a body of a patient.
 25. The system of claim 24, wherein thelithium-ion battery may be charged and recharged without removing thesystem from the body of the patient.
 26. The system of claim 23, whereinthe system is a neurological stimulation device.
 27. The system of claim26, wherein the neurological stimulation device is configured to providea therapeutic treatment to a patient by electrically stimulating aportion of the patient's brain.
 28. The system of claim 27, wherein theneurological stimulation device is configured to selectively provide aplurality of therapeutic treatments to a patient.
 29. The system ofclaim 23, wherein the system is selected from a cardiac defibrillator, acardiac pacemaker, a cardiac contractility modulator, a cardioverter, adrug administration device, a cochlear implant, a hearing aid, a sensor,a telemetry device, and a diagnostic recorder.
 30. The system of claim29, wherein the system is an implantable cardiac defibrillator forproviding a therapeutic high voltage treatment to a patient.
 31. Thesystem of claim 30, further comprising at least one lead extending fromthe defibrillator and configured for contacting a portion of a patient'sheart.
 32. The system of claim 23, wherein the positive electrode andthe negative electrode have a zero voltage crossing potential below thecorrosion potential of the negative current collector and above thedecomposition potential of the primary active material.
 33. The systemof claim 32, wherein the corrosion potential of the negative currentcollector is approximately 3.5 volts.
 34. The system of claim 23,further comprising a mass of lithium provided in electrical contact withthe negative current collector.
 35. The system of claim 34, wherein themass of lithium is configured to provide a lithium capacity for thenegative electrode sufficient to at least compensate for irreversibleloss of capacity of the negative electrode.
 36. The system of claim 35,wherein the mass of lithium is configured to provide a lithium capacityequal to the sum of the irreversible loss of capacity of the negativeelectrode and the capacity of the secondary active material.
 37. Thesystem of claim 23, wherein the negative current collector comprisescopper.
 38. The system of claim 23, wherein the first active material isselected from the group consisting of LiCoO₂,LiCo_(1/3)Mn_(1/3)Ni_(1/3), LiNi_(x)Co_(y)Al_(z)O₂,LiCo_(x)Ni_((1−x))O₂, and combinations thereof.
 39. The system of claim38, wherein the secondary active material comprises V₆O₁₃.
 40. Thesystem of claim 23, wherein the secondary active material comprises amaterial selected from the group consisting of V₂O₅, V₃O₈, MoO₃, TiS₂,WO₂, MoO₂, RuO₂, and combinations thereof.
 41. The system of claim 23,wherein the active material provided on the negative current collectoris a carbonaceous material.
 42. The system of claim 23, wherein theactive material provided on the negative current collector is a lithiumtitanate material.
 43. The system of claim 23, wherein the battery has acapacity between approximately 10 mAh and 1000 mAh.
 44. A method oftreating a medical condition of a patient by providing a therapeutictreatment to the patient, the method comprising: providing at least aportion of a medical device in contact with the patient; and discharginga battery to provide power to the medical device such that the medicaldevice provides the therapeutic treatment; wherein the batterycomprises: a positive electrode comprising a positive current collector,a first active material, and a second active material; and a negativeelectrode comprising a negative current collector, a third activematerial, and a quantity of lithium in electrical contact with thenegative current collector; wherein the first active material, thesecond active material, and the third active material are configured fordoping and undoping of lithium ions therefrom; and wherein the quantityof lithium provides electrochemically cyclable lithium for the secondactive material of the positive electrode to allow the second activematerial to exhibit charging and discharging capacity below a corrosionpotential of the negative current collector and above a decompositionpotential of the first active material; whereby the rechargeablelithium-ion battery may be discharged completely without a substantialreduction in battery capacity upon recharging.
 45. The method of claim44, wherein the step of providing at least a portion of the medicaldevice in contact with the patient comprises implanting at least aportion of the medical device in the patient.
 46. The method of claim45, wherein the battery may be charged and recharged without removingthe medical device from the body of the patient.
 47. The method of claim44, wherein the medical device is a neurological stimulation device. 48.The method of claim 47, further comprising providing a therapeutictreatment to a patient by electrically stimulating a portion of thepatient's brain.
 49. The method of claim 44, wherein the method isselected from a defibrillator, a pacemaker, a cardioverter, a cardiaccontractility modulator, a drug administration device, a cochlearimplant, a hearing aid, a sensor, a telemetry device, and a diagnosticrecorder.
 50. The method of claim 49, wherein the method is adefibrillator and further comprising providing a therapeutic highvoltage treatment to a patient.
 51. The method of claim 44, wherein thequantity of lithium is configured to provide a lithium capacity for thenegative electrode sufficient to at least compensate for irreversibleloss of capacity of the negative electrode.
 52. The method of claim 44,wherein the negative current collector comprises at least one of copper,titanium, aluminum, and nickel.
 53. The method of claim 44, wherein thefirst active material is selected from the group consisting of LiCoO₂,LiCo_(1/3)Mn_(1/3)Ni_(1/3), LiNi_(x)Co_(y)Al_(z)O₂,LiCo_(x)Ni_((1−x))O₂, and combinations thereof.
 54. The method of claim53, wherein the second active material comprises a material selectedfrom V₆O₁₃ and LiMn₂O₄.
 55. The method of claim 44, wherein the secondactive material comprises a material selected from the group consistingof V₂O₅, Li₄Ti₅O₁₂, Li_(x)VO₂, V₃O₈, MoO₃, TiS₂, WO₂, MoO₂, RuO₂, andcombinations thereof.
 56. The method of claim 44, wherein the thirdactive material is a carbonaceous material.
 57. The method of claim 44,wherein the third active material is a lithium titanate material. 58.The method of claim 44, further comprising a polymeric separatorprovided intermediate the positive electrode and the negative electrode.59. The method of claim 44, wherein the battery has a capacity betweenapproximately 10 mAh and 1000 mAh.
 60. The method of claim 44, whereinthe positive electrode and the negative electrode have zero voltagecrossing potentials below the corrosion potential of the negativecurrent collector and above the decomposition potential of the primaryactive material.
 61. The method of claim 44, wherein the negativecurrent collector comprises copper.